Yes, I know, the atom syntax doc does not make statements about what
happens in different feeds. But that does not mean that we are not
forced logically to a conclusion. There was a very in depth
discussion of this by the way on the atom semantics [1] mail list
this February.
I think the Atom Protocol is forcing the issue towards there being
only one entry per update time stamp. When you publish an entry with
an updated time stamp it is going to have to appear in a feed at some
point. And that won't be possible unless you overwrite one or the
other entries.
Also think of agregators. If you have the same entry with the same id
but different content, which is it going to choose?
Henry
[1] http://groups.google.com/group/atom-owl/browse_frm/thread/
357e36c4ee9cd31b/
On 7 Jun 2006, at 20:40, James M Snell wrote:
Henry Story wrote:
You can have two entries or feeds with the same id, as long as
they have
different updated time stamps.
That's not quite accurate. Two entries with the same atom:id may
appear
within the same atom:feed only if they have different atom:updated
elements. The spec is silent on whether or not two entries
existing in
*separate documents* may have identical atom:id and atom:updated
values.
Consider the case where my personal weblog publishes two Atom feeds.
One is a "full-content" feed that publishes content as XHTML. The
second is a "partial-content" feed that strips the markup and
publishes
content as plain text in the atom:summary while containing an
atom:content with a src attribute to the original XHTML. They
exist in
two separate Atom documents and both are based on the same underlying
blog post. The atom:id and atom:updated values for each entry are
identical.
Another example. I post an iCal file to an APP collection. In the
collection feed, I see a "media link entry" that uses content/@src to
point to the iCal. However, another feed that is used to provide a
summary of upcoming events has entries whose content element
contains an
XHTML rendering of the iCal files. Each entry in the summary feed
corresponds to exactly one entry in the APP collection; should they or
should they not use the same atom:id and atom:updated values?
- James
It's very much the same as you being Robert Yates all your life, but
having different sizes throughout your life. At any point in time you
have all the same properties...
Henry
On 7 Jun 2006, at 19:29, Robert Yates wrote:
This relates to work that we are doing with the publishing protocol,
but is syntax related.
In an implementation of APP a single entry can appear both in the
APP
collection and in any number of arbitrary feeds that the site
subsequently offers.
These feeds / collections can be optimized differently depending on
the client. For example, an entry in the collection feed may
have its
content "out of lined" whereas the "same" entry rendered in a
feed may
have its content inlined. There are other different optimizations
that we are investigating, that cause the entry representation in
various feeds / collections to be different, even though it has
originated from the same source.
So are these representations in the different feeds / collections
the
same entry or different entries? Should they have the same id?
and if
a feedreader comes across two entries with the same atom id,
what, if
anything, can it infer from that? is it only that they came from the
same source?
Many Thanks,
Rob
